First fire charge composition



June 30, 1953 McLAlN EI'AL 2,643,946

FIRST FIRE CHARGE COMPOSITION Filed March '7, 1945 JUSEPH H. MCLAIN THEODORE A. RUBLE Patented June 30, 1953 UNITED STATES PATENT QFFICE FIRST FIRE CHARGE COMPOSITION JosephH. McLain and Theodore A. Ruble, United States Army, assignors to the United States of America as represented by the Secretary of War Application March 7; 1945, Serial No. 581,538

'2 Claims. (Cl.'524) (Granted under Title 35, U. s. Code (1952),

sec. 266) The invention described herein may be manu.

had several disadvantages such as instability due topresence of moisture, backfiring due to lack of slag forming material and sensitivity to shock and friction. l

Briefly stated, the powder train compositions in one of the embodiments of our invention comprises a primer, first fire charge, a delay chargeand an ignition charge, all placed into'the central bore of the fuze body.

One of the objects of this invention is to provide a first fire charge, which will be extremely easy to ignite from primer or powder flash and yet not sensitive enough to frictional impact to cause undue hazard in mixing or pressing procedures. This charge must be relatively gasless and have a high burning temperature to act as arelay between a primer and some less sensitive material such as the delay charge.

. Another object of this invention is to provide a material which will not deteriorate in storage at high temperatures and humidities and also possess the usual physical requirements as to ease of mixing, ability to flow and to pelleting.

Another object of this invention is to provide a delay. charge that would meet the following requirements: It should be gasless, non-hygroscopic and, on burning, should leave a plugforming residue. It should be insensitive to friction and impact and should possess ease of ignition and. propagation with ability to be granulated and pelleted and it should burn with sufficient heat to ignite starter mixtures. The speed of burning should be adjustable by varying proportions of the ingredients.

Another object of this invention is to provide an ignition charge that would be non-hygroscopic, withstand long periods of storage under severe conditions of temperature and humidity, be readily ignitable, yet neither friction nor impact sensitive to the degree causing the compounding to be hazardous for safe manufacture.

It must possess a high burning temperature with a large amount of gas and flash so as to be able charge 4 comprises:

Other objects of this invention will be apparent to those skilled in the art upon reading the specificat on in conjunction with the accompanyin drawing in which the single figure is a vertical section'of the top portion of a grenade provided with a fuze incorporating the various features of this invention.

Referring to the drawing, a grenade is indicated generally at 8, provided with a fuze indicated generally at 9. Except for the powder train to which this invention particularly pertains the fuze 8 is of the type heretofore utilized by the Army in connection with various types of munitions and is described on pages 299-307 of Chemicals in War. by A. M Prentiss, edited by McGraw-Hill Book .Co; Inc., New York and London, 193 7. r I

The, preferred composition of the first fire Red lead i Silicon 33.752 Manganese 11.2:1 1 Celluloid l 1.8:02

It wasfound in practice that this mixture is extremely easy toignite' from primeror powder 1 operations. It is gasless and has a high burning to ignite the various materials used with it as starter mixes in munitions of various types.

The fuze of one Of the embodiment of our invention is easily manufactured, exhibits better over all functioning both before and. after extreme storage conditions and will withstand immersion in water for at least four hours.

temperature so that it acts as a relay between a primer and the delay charge. This material was found to be stable in storage under severe conditions of temperature and humidity. The specific proportions appear to be critical.

Percent Litharge 76.9 Silicon 19.3 Fullers earth 1.5 Celluloid 1.8 Graphite 0.5

This composition was found to withstand tropical storage for at least 3 months with 96.9% functioning. It is pelleted and loaded into the fuze 9 in the manner described hereinafter.

Burning time of this delay mixture can be varied by changing the proportions of litharge and silicon within the range of from 20% silicon- 80% litharge to silicon-95% litharge. This property enables this mixture to be used in other types of munitions.

The delay charge of this type, when burned,

leaves a heavy slag to serve as a plug and to prevent backfiring in this type of fuze.

The ignition charge 3 forms one of the embodiments of our invention and comprises an intimate mixture of Per cent by Weight Lead chromate 59:5

Silicon 19.613 Magnesium 19.613 Celluloid 1.8102

This mixture is non-hygroscopic and is capable of withstanding long periods of storage under severe conditions of temperature and humidity. It is readily ignitible, but insensitive to friction or impact, thus eliminating the hazards ofprocessing steps. This material must be in granular form and must flow readily to facilitate loading. In manufacture, this composition is mixed dry in the presence of approximately by Weight of an 8%" solution of celluloid sheet inacetone. While still moist, this material is granulated and allowed to dry. i i

This composition replaces the usual black powder; 'ordinarily 'used in fuzes of this type. It gives a largefiashand alarge amount of gas.

The Size-"ofthe flash obtained from this igni-, tion charge can be varied by changing the particle size of the granulated mixture within the range of from through 20' mesh to held on 200 mes hl The larger particle size produces the greater flash.

Injthe preferred embodiment of this invention, the loading of the'igniter fuze 9 is efiected in the following manner.

The fire'charge 4 in a form of a smallpellet (0.188':.008-.-in diameter weighing 0.300 to 0.400. gram, O.200"i.010" in height) and a pellet of charge. delay '2 (Weighing- 0.6001050 gram, 0300-71015inheight and 0.008" in diameter) are pressed in place beneath the primer 5- in the fuze body H] under a dead load pressure of 400- 600 lbs. Another delay charge pellet 2 is added and consolidated in the'same manner, as shown. In order to improve the propagation of burning, a keyed ram tip is used for thepressing operations'.

This isfollowedby a loose mixture of ignition charge 3 sufficient to fill. the cavity. A closing disc 6 is then crimped in place and. the-whole is- 4 v. :a.terpr.oofed with. a solution of 40 wax material in a mixture of benzol and toluene (equal parts by weight) by brush application as is well known in this art.

The topv portionof the fuze is protected by an aluminum foil disc 1 stamped into the fuze body and its periphery sealed with a coat of wax and shellac varnish.

'Ih fuze 9' is then assembled, as shown, with striker, lever, etc., in accordance with the normal procedure well known in this art.

Thefuze of this invention is economical to manufacture and exhibits better over all functioning both before and after extreme storage conditions. It will withstand immersion in water for at least 4 hours without showing any defects in use.

In the foregoing description we described the preferred embodiment of the invention without confining ourselves to the precise details set forth byway of illustration, as it is apparent that many changes and variations may be made therein by those skilled in the art, without departing from the spirit of the invention or exceeding the scope of the appended claims.

We claim:

.1. A first fire mixture composed of red lead 533%, silicon 33.7%, manganese 11.2%, and Celluloid 1.8%.

2. .A fire mixture to be ignited by a primer,

which mixture comprises red lead 53.3:2%,silicon 33,.7i2,% manganese 11.2:1% and Celluloid 1.8:0.2%.

Jossen l-I. MCLAIN.

- THEODORE. A. RUBLE.

References. Cited. in the file of. this patent VUNITED STATES PATENTS 

2. A FIRE MIXTURE TO BE IGNITED BY A PRIMER, WHICH MIXTURE COMPRISES RED LEAD 53.3$2%, SILICON 33.7$2%, MANGANESE 11.2$1% AND CELLULOID 1.8$0.2% 